The invention is generally in the field of a gas and liquid contact apparatus with a gas inlet and outlet.
In the past, various methods and apparatus have been used to aerate a body of liquid, such as a lagoon of water and waste material. Such apparatus often includes means for introducing bacteria or chemicals into the water as well as aeration. A typical approach has been to employ mechanical impellers within the liquid to discharge the liquid into the atmosphere, whereupon the discharged liquid falls back into the body of liquid. A drawback to this approach is that discharging the water into cold air has a cooling effect on the water which slows the desired aerobic bacteria action severely.
Another approach has been to employ mechanical pumping apparatus located within the body of liquid to pump liquid from a given depth or location through an intermediate aerating step and thence to another level or location in the body of liquid. Such a mechanical apparatus suffers from the drawback that in case of a power failure in cold weather, the working parts of the pump or impeller may become frozen, plus the general wearing and damaging effects of the pump and impeller being in contact with the liquid.
Fixed position diffuser elements may be mounted within the body of liquid to aerate or otherwise treat the liquid, but such fixed positioned diffusers are difficult to repalce or clean and therefore a good diffuser nozzle cannot be used on this type of system because of service problems; therefore, the nozzles are large and don't give an economical oxygen transfer.
According to an embodiment of the present invention, a floating draft tube aerator is provided which utilizes compressed air diffusion beneath the surface of the liquid but in conjunction with a movable apparatus having an accessible diffuser nozzle. The air compressors for such apparatus can be housed on shore out of the weather and not exposed to the elements or corrosive liquids as are mechanical aerators. Compressors of the type used in this application are simple in design, easy to repair and normally of long life.
The present floating draft tube aerator eliminates the need for installation of tubes or airlines in muddy bottoms of lagoons, etc. The present aerator also eliminates the possibility of error in computing the required amount of air as can occur in bottom installed systems, due to the fact that the presently disclosed floating units can easily be moved to close or open the diffuser pattern, as oxygen demands dictate. Additional units can be added for peak loads, such as tourist influx, and can be shut down when not needed, by using separate compressors for a given number of aerators. The blower compressors used generate their own heat and can be housed on shore out of the weather, without auxiliary heat or the worry of freezeups.